OTTAWA, Ontario — There still is debate about whether genetically modified (GMO) crops have an increased yield compared to their non-GMO counterparts. Promoters of GMO products say they do, while critics of the technology allege they don’t – and even that they may decrease yields.

“There’s no question that there’s no GM trait for higher yields, per se,” said Lucy Sharratt, coordinator of the Canadian Biotechnology Action Network (CBAN). “There’s an argument that the GMOs increase yields operationally, but not because of the plants themselves.”

Sharratt points to a report from the Union of Concerned Scientists from 2009 called Failure to Yield, authored by Doug Gurian-Sherman. He wrote that GMO soybeans have not increased yields at all and that GMO corn has increased yields only marginally on a crop-wide basis.

“Overall, corn and soybean yields have risen substantially over the last 15 years, but largely not as a result of the (GMO) traits,” he concluded. “Most of the gains are due to traditional breeding or improvement of other agricultural practices.”

Sharratt said any yield advantages from GMO corn and soybean traits are beginning to disappear because the traits are “actually failing as predicted. Everyone knew that this would happen, and it is happening.”

She said insects are developing resistance to the GMO corn and that weeds are developing resistance to the herbicide glyphosate, which she believes is bound to nullify whatever advantages those traits have.

But Sharratt said the problem extends beyond the issue of crop yields alone. She said the biggest seed companies are putting GMO traits on top of many of the high-yield varieties. These companies – Monsanto, DuPont, Dow, Syngenta, Bayer and BASF – control nearly 60 percent of the seed supply worldwide, and these same companies also control 76 percent of agrochemicals, she said.

“The more seeds they control, the more market control they have,” she stated. “Many farmers we’ve talked with say they can’t find soy or corn without GM traits. If only a few companies own all the seed, then it’s up to them how they sell the seed or even if they want to sell the seed.”

Monsanto Co., one of the largest seed firms and developer of Roundup Ready soybeans, claims GMO products are increasing yields. The company states GMO crops generally have higher yields because of breeding and technology. It also says marker-assisted breeding has nearly doubled the rate of yield gain when compared to traditional breeding alone.

It points to a report by PG Economics from 2009 called Focus On Yields, which reported on GMO yields in various countries. According to the report, between 1996-2007, in all the countries studied, the crops had significant yield increases attributable to biotechnology.

These included soybeans at 67 million metric tons (mmts), corn at 62 mmts, cotton at 6.85 mmts and canola at 4.44 mmts. During this period the area planted to GMO soybeans increased nearly 30 percent.

According to the report, in Romania, for example, herbicide-tolerant (HT) soybeans improved the average yield by more than 30 percent and GMO HT corn in Argentina and the Philippines delivered yield improvements of 9 and 15 percent, respectively.

The study also stated a positive byproduct of HT soybeans is the adoption of no-tillage production systems, which shorten the production cycle.

“This advantage enables many farmers in South America to plant a crop of soybeans immediately after a wheat crop in the same growing season,” it stated. “This second crop, additional to traditional soybean production, has added 67.5 million (metric) tons to soybean production in Argentina and Paraguay between 1996 and 2007.”